I believe it is necessary to avoid oversimplification here. As Neuroanatomist has pointed out there is always some absorption leading to a loss of color fidelity based on the materials used in any given lens, which is the key to understanding what is actually going on. Here's an article on the subject for further reading:http://en.wikipedia.org/wiki/Absorption_%28electromagnetic_radiation%29
We are using different lenses, which have different properties as to how they affect light (= electromagnetic radiation visible to the human eye) passing through them. In general we may assume/hope that more expensive lenses offer better images, because the more expensive material used in them has better characteristics for providing what appears to be "better" images.
Now what is the effect for a photographer?
Using some of the most highly prized lenses (as in most praise, not as in most costly) you will find that you can take shots that look similar to what you have seen, while with worse lenses you will end up with what is usually described as a flat look. Somehow, something is missing and although you look at what may pass as an adequate image of the scenery, you are missing something. Of course you can't point out that some of the wavelengths have been affected adversely by your lens, because this would be too blunt an effect, but you will see the effect nonetheless.
It is important to note that you cannot fully compensate for such effects in post-processing, because the software you use will never know just exactly what and how much of what has been lost due to the lens. Adding colour in post-processing can only compensate for a more general effect, such as for example a sky not blue enough or less vibrant green leaves compared to what you remember. This will enable you to make general corrections, but you will not be able to fully recompose the exact mood of the scenery as you have seen it before. Granted some post-processing artists may come very close.
I just think about the time lost in post-processing as opposed to time spent actually taking pictures. You decide what is preferable to you. Although I am quite happy with Adobe Lightroom I rather take pictures